A Texas woman faces trial this month in Austin on charges she threatened to kill a government informant who infiltrated an Austin-based group that planned to bomb the Republican National Convention in St. Paul, Minn., last fall.

Katyanne Marie Kibby, 25, was indicted in June by a federal grand jury in Austin. She is accused of retaliating against Brandon Darby, the community activist-turned-informant who helped federal prosecutors win convictions against Bradley Neal Crowder, 24, and David Guy McKay, 23.

Prosecutors say the e-mail threat was made Jan. 10. That was two days after Crowder reached a plea bargain with federal prosecutors in Minneapolis for his role in the plot to build Molotov cocktails and attack the GOP convention in September 2008.

Crowder and McKay were part of a group of activists that had gone to the Twin Cities to take part in street demonstrations. The FBI had infiltrated the group with Darby. Crowder and McKay built eight of the gasoline firebombs but didn't use them, a fact law enforcement officials credited to Darby.

Members of the Austin protest community heaped scorn on Darby, saying he had betrayed longtime friends and colleagues.

Kibby, who lives in Houston, is free on bond. If convicted, she could face 20 years in prison and a $250,000 fine. She could not be reached for comment.

Federal prosecutors and Kibby's public defender have about a week to reach a plea agreement. If they don't, her trial is to begin Aug. 31 in U.S. District Court in Austin.

Neither her attorney, Jose Gonzalez-Falla, nor Assistant U.S. Attorney Gregg Sofer returned calls for comment. Darby, who lives near Austin, also did not return a call for comment.

The single-count indictment says Kibby "did knowingly engage in conduct threatening bodily injury" to Darby. It says she sent an e-mail that threatened his life "for giving information to a law enforcement officer."

The indictment doesn't say what was in the e-mail.

Darby, originally from Houston, had earned a national reputation as an activist in New Orleans after Hurricane Katrina struck in August 2005. He was a co-founder of the Common Ground Collective, whose members delivered food, water, supplies and medical care to people in the flood-ravaged city.

But Darby said that he grew disenchanted with some beliefs and tactics used by more radical activists. That disenchantment led to contacts with the FBI, and in November 2007, federal agents asked him to work as an undercover informant.

Federal agents asked him to infiltrate a loose-knit group of activists in Austin that included McKay, who did part-time graphics work at an ad agency, and Crowder, who worked in a sandwich shop.

In the months leading up to the GOP convention in St. Paul, the FBI was concerned that some groups planning to converge on St. Paul had less-than-peaceful demonstrations in mind.

Darby accompanied the group to St. Paul. McKay and Crowder later built eight Molotov cocktails, and alternately planned to bomb either a truck with a large TV screen or a parking lot used by law enforcement officers, according to later testimony.

McKay and Crowder were charged in September. A little over a month later, Darby's work as an informant was disclosed by the Pioneer Press.

Crowder pleaded guilty in a deal with prosecutors, but McKay took his case to trial. Darby was the key witness against him.

When McKay testified in his own defense, he claimed Darby entrapped him. He told jurors that had it not been for Darby's urgings, he never would have built the Molotov cocktails.

The jury couldn't reach a verdict and a judge declared a mistrial. Before a second trial was to begin, federal prosecutors said Crowder would be called to testify against McKay, who then accepted a plea bargain.

Crowder was sentenced to two years in prison and is scheduled for release in May 2010.

McKay was sentenced to four years in prison and is due to get out in April 2012.